Fact: Perchlorate does not damage the thyroid gland. High levels of perchlorate, above 245 parts per billion (ppb), can temporarily affect the thyroid's ability to absorb iodide from the bloodstream, but this in itself is not an adverse effect (it happens naturally in every human as a result of diet and other factors). An adverse health effect would require daily consumption of more than 14,000 ppb in drinking water. Perchlorate is not stored in any human tissues, including the thyroid gland.

Myth: Perchlorate in drinking water is dangerous in any amount.

Fact: Credible, published scientific studies have shown that the perchlorate levels found in a small number of drinking water supplies have no measurable effect on human health. It is important to underscore that drinking water supplies in California, for example, are meeting strict goals for perchlorate, generally in the 4 ppb to 6 ppb range. In contrast, when perchlorate has been used as a medicine to treat overactive thyroid glands, levels tens of thousands of times higher than what's being found in drinking water have been needed to have the desired effect. An adverse health effect would require daily consumption of more than 14,000 ppb in drinking water.

Myth: Perchlorate is rocket fuel.

Fact: Perchlorate is a salt, which exists naturally in some fertilizers and can be man made. Because of the large amounts of oxygen in its chemical make up, it is used as an oxidizer to help solid rocket fuel burn.

Myth: Low levels of perchlorate can cause birth defects and are harmful to young children.

Fact: A review of the research shows that the low levels of perchlorate found in drinking water do not harm newborns or young children. These include:

Tellez et al. This study found no impacts from perchlorate on pregnant women during the critical period between the late first and early second trimesters, and no effect on fetal development or thyroid levels in newborns. The study examined pregnant women and babies from three cities in Chile, where perchlorate levels range from non-detect to 110 ppb, and daily intake of dietary iodide is equivalent with the U.S.

Kelsh et al. This study evaluated whether newborns had higher rates of primary congenital hypothyroidism (PCH) or elevated concentrations of thyroid-stimulating hormone in a community where perchlorate was detected in groundwater wells. The findings, according to the Journal of Occupational and Environmental Medicine, suggest that residence in a community with potential perchlorate exposure has not impacted PCH rates or newborn thyroid function. View Abstract

Li et al. A comparison of standard test results of newborns in two cities in Nevada, one with perchlorate in its drinking water and one without.

These findings provide reason to believe that low levels of perchlorate also have no measurable effect on pregnant women or fetuses. This was confirmed by the NAS report, which included a total uncertainty factor of 10 when recommending a reference dose of perchlorate at 0.0007 milligrams per kilogram per day. According to the NAS, this number protects the most sensitive population - the fetuses of pregnant women who might have hypothyroidism or iodide deficiency.

Myth: Perchlorate must be removed from water to the point where it cannot be detected, no matter what the cost.

Fact: In February 2005, the U.S. Environmental Protection Agency (EPA) established its official reference dose of perchlorate at 0.0007 milligrams per kilogram per day, and translated that number to a Drinking Water Equivalent Level (DWEL) of 24.5 ppb. This level is consistent with the recommended reference dose included in the NAS report. Both the NAS and the EPA state that these numbers are appropriate and protective for all populations, including the most sensitive population - the fetuses of pregnant women who might have hypothyroidism or iodide deficiency. Further, because low levels of perchlorate (below 245 ppb) have no measurable effect on human health, (and levels below 14,000 ppb have no adverse effect) total removal of perchlorate serves no purpose. In fact, doing so could cost millions of taxpayer dollars for treatment facilities and/or replacement water supplies, taking resources away from other, real health issues, while potentially causing severe water shortages - all without providing any public health benefit.

Myth: Perchlorate is unstable and can explode.

Fact: Perchlorate is extremely stable when dissolved in water. It is impossible for the perchlorate found in any water to explode.